Electrical receptacle having zero potential until an electrical plug is positioned therein and including circuit breaker means



c. GARAMSZEGI 3,370,141

CIRCUIT BREAKER MEANS 3 Sheets-Sheet 1 Feb. 20, 1968 ELECTRICAL RECEPTACLE HAVING ZERO POTENTIAL UNTIL/AN ELECTRICAL PLUG IS POSITIONED THEREIN AND INCLUDING Filed Oct. 21, 1965 I NVEN TOR ATTORNEYS.

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Z Y fi n" w m 7 r III .H. B ll Ill Ma :5 JAKAMSZZG/ BY i; {Z a C. GARAMSZEGI Feb. 20, 19 8 v ELECTRICAL RECEPTACLE HAVING ZERO POTENTIAL UNTIL AN ELECTRICAL PLUG IS FOSITIONED THEREIN AND INCLUDING CIRCUIT BREAKER MEANS 3 Sheets-Sheet 2 Filed 001;. 21, 1965 3 N W M l M l I: Q 2 5 5 ,v 5 VIM/q w 00 0 Z w M m as w INVENTOR. [max fi/w/wsza/ ATTORNEYS.

Feb. 20, 1968 c. GARAMSZEGI 3,370,141

ELECTRICAL RECEPTACLE HAVING ZERO POTENTIAL UNTIL AN ELECTRICAL PLUG IS POSITIONED THEREIN AND INCLUDING CIRCUIT BREAKER MEANS Filed Oct. 21, 1965 3 Sheets-Sheet 6 Z6 BY [44am 6/154 MSZfG/ INVENTOR.

ATTORNEYS;

United States Patent O 3,370,141 ELECTRICAL RECEPTACLE HAVING ZERO PO- TENTIAL UNTIL AN ELECTRICAL PLUG IS POSITIONED THEREIN AND INCLUDING CIR- CUIT BREAKER MEANS Charles Garamszegi, 73 Woodrow St., West Hartford, Conn. 06107 Filed Oct. 21, 1965, Ser. No. 499,509 15 Claims. (Cl. ZOO-115.5)

This invention relates to an electrical wall receptacle, and more particularly to a wall receptacle of the type delivering zero potential to the outlet terminals until an electrical plug is positioned in electrical communication with the terminals.

It is known in the prior art to provide a wall receptacle having the general characteristics mentioned but it is unfortunate that they include such disadvantages as have precluded their general adoption. Foremost among these disadvantages is one of expense since the wall receptacles of the prior art provide only a single safety feature resulting in the added expense because of the components needed to perform such safety functions with all the remaining components of a conventional building electrical circuit still being required.

It is an object of the instant invention to provide a Wall receptacle providing an electrical potential only when a removable electric plug is associated therewith and which includes means for severing the electrical circuit through the wall receptacle upon the passage of current thereth-rough above a predetermined value.

Another object of the instant invention is to provide a wall receptacle of the character described which may be utilized in the wiring of a new building circuit or in the rewiring of an old building circuit which obviates the requirement of a plurality of centrally disposed circuit breaker or fuse stations.

Still another object of the instant invention is to provide a wall receptacle such that a plurality thereof may be attached in parallel to a single branch line such that the overload of a single receptacle will not de-energize the entire branch line.

A further object of the instant invention is to provide a wall receptacle including a circuit severing mechanism which may be reset merely by removing an associated electrical plug and replacing the same.

A still further object of the instant invention is to provide a wall receptacle having the following operational characteristics: the removal of an associated electrical plug results in a zero potential across the outlet terminals for safety purposes, an electrical potential is applied to the outlet terminals only when an electrical plug is partially engaged with the receptacle, the imposition of current flow through the receptacle above a predetermined value automatically severs the wall receptacle circuit, and the removal of an associated plug automatically conditions the receptacle for delivery of electrical potential although zero potential. will exist across the outlet terminals until the associated plug is placed in engagement therewith.

Still another object of the instant invention is to provide a wall receptacle-of the character described including means for severing the Wall receptacle circuit upon the imposition of current flow therethrough at a prolonged rate slightly above the predetermined safety limit.

A further object of the instant invention is to provide a wall receptacle of the character described including means for severing the wall receptacle circuit upon the imposition of an impulse current flow substantially above the predetermined safety limit.

Other objects and advantages of the instant invention,

"ice

as well as the invention itself, reside in the combinations of elements, arrangements of parts, and features of construction and operation, all as will be more full pointed out hereinafter and disclosed in the accompanying drawings wherein there are disclosed preferred embodiments of this inventive concept.

In the drawings:

FIGURE 1 is a front elevational view of a Wall receptacle secured in operating position in a building wall;

FIGURE 2 is a horizontal enlarged cross-sectional view of the wall receptacle of FIGURE 1 taken substantially along line 2-2 thereof as viewed in the direction indicated by the arrows illustrating a single unit for controlling current fiow to a pair of outlet terminals, showing the electrical circuit thereof in a closed current delivering condition;

FIGURE 3 is a horizontal enlarged cross-sectional view similar to that of FIGURE 2 showing the wall receptacle unit in a current severing condition to preclude the delivery of electrical potential to the outlet receptacles with a removable electric plug positioned adjacent thereto; Y

FIGURE 4 is a view of the receptacle units of FIG- URES 2 and 3 with the electrical plug removed;

FIGURE 5 is a cross-sectional view of an alternate form of positioning means for energizing the outlet terminals upon the insertion of an electrical plug showing the relative positions of the components when the plug is not inserted therein;

FIGURE 6 is a partial cross-sectional view of the alternative device of FIGURE 5 with a single probe inserted therein;

FIGURE 7 is a partial cross-sectional view of the alternative device of FIGURE 5 showing the movement of the locking components by an electric plug; and

FIGURE 8 is a schematic view of the electrical circuit and mechanical operating devices necessary to operate the wall receptacle of the instant invention.

OVERALL CONSTRUCTION AND OPERATION Referring now to the drawings in detail, wherein like reference characters designate like elements throughout the several views thereof, and particularly to FIGURE 1, there is indicated generally at 10 a wall receptacle having a rectangular face plate 12 forming two sets of diagonally spaced pairs of prong receiving slots 14 with plate 12 being secured by suitable frictional fasteners 16, such as screws or the like, to a wall 18 of a building structure. Referring now to FIGURES 2 to 4 inclusive, there is indicated generally at 20 a conventional removable male electric plug having a suitable power cord 22 leading to a plug 24 and electrically connected to a pair of male slots 14.

Wall receptacle 10 includes a dielectric frame shown generally at 28 affixed to face plate 12 and forming a pair of openings indicated generally at 30, 31 for receiving prongs 26 of electric plug 20. Wall receptacle 10 also includes a mounting means shown generally at 32 providing relative movement between a first fixed contact 34 and a second movable contact 36 with a motion transmitting means designated generally at 38 being engageable with prongs 26 for selectively positioning contacts 34, 36 in the closed position shown in FIGURE 2. A power delivery circuit denominated generally at 40 in FIGURE 8 provides electrical communication between contacts 34, 36 and a pair of outlet terminals shown generally at 42, 44 and openings 30, 31 through a circuit opening means designated generally at 46 for opening power delivery circuit 40 upon the flow of current through above a predetermined limit.

prongs 26 inserted in prong receiving.

Power delivery circuit 40 includes a pair of electric wires 48, 50 which may be connected to a suitable power source for delivering alternating current therethrough. As may be seen in FIGURE 8, wire 50 is connected to outlet terminal 44 with wire 48 being connected to contact 34 for engagement with movable contact 36 and subsequent electrical connection through mounting means 32, circuit opening means 46 and outlet terminal 42. As will be explained more fully hereinafter, the insertion of electrical plug 20 into openings 30, 31 results in the manipulation of motion transmitting means 38 to close contacts 34, 36 thus resulting in a closed power delivery circuit delivering electrical potential across outlet terminals 42, 44 for operating an appliance connected to plug 20. As will also be more fully explained hereinafter, the delivery of current through power delivery circuit 40 at a rate slightly greater than a predetermined value or at an impulse rate substantially greater than the predetermined value will result in the activation of circuit opening means 46 to manipulate mounting means 32 for moving contacts 34, 36 to the open position ceasing the delivery of current to terminals 42, 44.

It will be seen, therefore, that wall receptacle provides a first safety feature in preventing the delivery of electrical potential to outlet terminals 42, 44 until plug is inserted, thus precluding a small child from being injured thereby. Another safety feature is present in wall receptacle 10 to cease current flow through circuit 40 when the rate thereof is slightly greater than a predetermined value, such as will occur upon a prolonged overload of the system. A saill further safety feature is present by providing means for interrupting power deivery circuit 40 when the current flow therethrough is very high, such as may occur during a shorting-out of plug 20 or the appliance to which it is attached. As will be more fully explained hereinafter, a still further advantage resides in wall receptacle 10 since mounting means 32 and motion transmitting means 38 are so constructed and arranged to allow the reset of circuit 40 to pass current therethrough upon the removal of plug 20.

FRAME AND OUTLET TERMINAL CONSTRUC- TION As previously indicated, frame 28 is made of a dielectric material and includes a first panel 52 providing a support for mounting means 32, motion transmitting means 38 and circuit opening means 40, a second panel 54 and a third panel 56. Panels 52, S4, 56 are substantially aligned and spaced slightly apart to form openings 30, 31 therebetween in order to receive male prongs 26.

Secured to third panel 56 is a S-shaped bracket designated generally at 58 having a first leg 60 secured to the forward face thereof a second leg 62 secured to panel 56 facing opening and carrying a reverted prong which constitutes outlet terminal 44. A third leg 64 extends rearwardly of second panel 54 and is electrically separated therefrom providing connection between a releasable connector 66 securing electrical input wire 50 to bracket 58. Since bracket 58 is made of an electrical conductor, such as copper, it will be seen that one side of power delivery circuit is complete.

Outlet terminal 42 is releasably secured to second panel 54 by a metal U-shaped bracket 68 and a threaded screw 70. Outlet terminal 42 is biased by its own construction and characteristics toward first panel 52 and includes a lower bent end 72 forming an arcuate camming surface 74 at the junction thereof. As may be seen most clearly in FIGURE 4, opening 31 is displaced slightly from slot 14 such that prong 26 will contact arcuate camming surface 74 when inserted into opening 31 insuring close electrical contact therebetween. As may also be seen most clearly in FIGURE 4, outlet terminal 42 forms an elongate longitudinal slot 76 for receiving part of motion transmitting means 38 as will be more fully explained hereinafter.

Second panel 54 forms a cutout 78 adjacent face plate 12 for receiving bent end 72 when plug 26 is inserted into opening 31 as may be seen in FIGURES 2 and 3. Second panel 52 also forms a triangular cutout 80 aligned with slot 76 in outlet terminal 42 to receive part of motion transmitting means 38 as may be seen in FIGURE 4.

MOUNTING MEANS Mounting means 32 includes a stationary metal L- shaped bracket 82 having one leg thereof secured to face plate 12 by a plurality of suitable frictional fasteners 84, such as rivets, screws or the like, with the short leg thereof carrying fixed contact 34 in a substantially vertical attitude. Electrical input wire 48 is releasably secured in a conventional manner to the long leg of L-shaped bracket 82 by a screw 86.

Mounting means 32 includes a load carrying arm designated generally at 88 forming a horizontal elongate slot 90 receiving therein a pivot pin 92 positioned vertically above the short leg of L-shaped bracket 82 and equipped with an enlarged head 94 precluding inadvertent outward movement of load carrying arm 88. A contact carrying arm 96 is a downwardly extending part of load carrying arm 88 and carries movable contact 36 for selectively positioning contact 36 against and away from stationary contact 34 as may be seen by a comparison of FIGURE 2 with FIGURES 3 and 4. Load carrying arm 88 forms a protuberance 98 connected to an electrical wire 100 leading to circuit opening means 46 as will be explained more fully hereinafter, with an upwardly extending latching arm 102 extending substantially above pivot pin 92 and protuberance 98 as will also be explained more fully hereinafter.

Pivot pin 92 is rigidly fastened to a positioner shown generally at 104 which is pivotally mounted about a pivot pin 106 securely fastened to first panel 52 of frame 28. It will be seen, therefore, that load carrying arm 88 undergoes three types of movement, rotating about the axis of pivot pin 92, rotating along with positioner 104 about the axis of pivot pin 106 and slidably moving with respect to positioner 104 through the coaction of slot 90 and pivot pin 92.

MOTION TRANSMITTING MEANS In addition to being a part of mounting means 32, positioner 104 also constitutes a component of motion transmitting means 38 and includes an irregularly configured planer plate 108 having a right-angled segment 110 positioned adjacent load carrying arm 88 to the left of pivot pin 92 as may seen in FIGURES 2 to 4 inclusive. Propelling positioner 104 and load carrying arm 88 in a clockwise direction about pivot pin 106 is a return spring 112 coiled about pivot pin 106, bearing against face plate 12 and secured, as by welding or the like, to segment 110. Plate 108 forms an upwardly and outwardly extending L-shaped arm 111 carrying a rearwardly extending flange 113 with a helical spring 114 biasing apart flange 113 and a rearwardly extending flange .116 on load carrying arm 88.

Motion transmitting means 38 also includes a cam designated generally at 118 including an arm 120 pivotally mounted by a pivot pin 122 on first panel 52 carrying a cam lug 124 presenting an involute camming surface 126. A connecting block 128 is pivotally mounted by a pivot pin 130 secured between first panel 52 and a support block 132 affixed to face plate 12.

FIGURE 4 illustrates the starting position before plug 20 is inserted into openings 30, 31 through slots 14. It should be pointed out that contacts 34, 36 are in the open position precluding the flow of electrical current through power delivery circuit 40 consequently resulting in a zero potential across outlet terminals 42, 44. As prongs 26 are inserted into openings 30, 31, the leftmost prong in FIG- URE 2 will contact arcuate camming surface 74 of outlet terminal 42 thus pivoting bent end 72 into cutout 78 allowing for the passage of leftmost prong 26. A prong will then contact connecting block 128 and begin pivoting it in a counter-clockwise direction about pivot pin 130 as may be seen in FIGURE 2. Connecting block 128 will contact involute camming surface 126 of cam 118 with another portion of camming surface 126 contacting rearwardly extending flange 113 of positioner 104.

Accordingly, positioner 104 and load carrying arm 88 will begin a counter-clockwise rotation about the axis of pivot pin 106 as may be seen in FIGURE 2. A rearwardly extending flange 103 of latch arm 102 will come in contact with a notch 134 of a pivoted armature plate shown generally at 136 of circuit opening means 46 thereby preeluding further counterclockwise rotation of arm 88. Continued insertion of prongs 26 into openings 30, 31 will pivot connecting block 128 an additional increment .resulting in further counter-clockwise rotation of positioner 104. During this incremental rotation of positioner 104, segment 110 thereof bears against load carrying arm 88 at a point slightly above pivot pin 92 to allow helical spring 114 to slide load carrying arm 88 with respect to pivot pin 92 thus resulting in the closing of contacts 34, 36.

Inserting prongs 26 an additional increment into openl ings 30, 31 will result in additional rotation of connecting block 128 and cam 118 to further rotate positioner 104 in a counter-clockwise direction. During this additional incremental rotation of positioner 104, load carrying arm 88 will be secured against rotation by contact with notch 134 and stationary contact 34. Accordingly, slot 90 and pivot pin 92 act as a lost motion connection between positioner 104 and load carrying arm 88. FIGURE 2 illustrates the completed insertion of plug 20 into receptacle with the counter-rotation of the components of mounting means 32 and motion transmitting means 38 being precluded by the positioning of prong 26 in opening 31. It should now be apparent that an electrical path including electrical input wire 48, L-shaped bracket 82, Station my contact 34, movable contact 36, load carrying arm 88, protuberance 98 and wire 100, is completed.

CIRCUIT OPENING MEANS Circuit opening means 46 includes an L-shaped bracket 138 vertically secured to first panel 52 by a U-shaped connector 140 and a plurality of frictional fasteners 142, such as screws or the like. Fixedly secured to the long leg of L-shaped bracket 138 by a pair of frictionalfasteners 144 is a substantially U-shaped member 146 having the upper leg thereof extending above Lshaped bracket 138 with the lower leg of member 146 being connected to wire 100. Fixedly secured on the upper end of U-shaped member 146 is a bimetallic strip 148 having upper and lower layers of metals having different coefiicients of thermal expansion. In the illustrated device the upper layer of strip 148 should have the higher coefficient for reasons more fully explained hereinafter.

Electrical wire 150 connects the free end of bimetallic strip 148 to the winding of a solenoid shown generally at 152 while another electrical wire 154 connects the other side of the winding of solenoid 152 to releasable screw 70 on second panel 54. It will thus be seen that power delivery circuit 40 is completed upon the juxtaposition of contacts 34, 36 in order to deliver electrical energy to outlet terminals 42, 44. Conversely, the opening of contacts 34, 36 will sever power delivery circuit 40 thus precluding the development of electrical potential across outlet terminals 42, 44.

Armature plate 136 is pivotally mounted on an inturned upper end 155 of L-shaped bracket 138 and is provided with an aperture through which a plunger 156 of solenoid 152 extends. An enlarged boss 158 may be secured to the terminal end of plunger 156 with a helical spring 160 surrounding plunger 156 for slidably positioning armature plate 136 adjacent boss 158.

In the operation of circuit opening means 46, the infit sertion of plug 20 in openings 30, 31 will complete power delivery circuit 40 as previously mentioned. Should a short occur in the appliance to which plug 20 is attached, a sufliciently high current impulse will pass through solenoid 152 retracting plunger 56 and depressing armature plate 136. Since helical spring 114 is biasing positioner 104 and load carrying arm 88 apart, flange 103 of latch arm 102 will clear notch 134 with load carrying arm 88 being pivoted in a counter-clockwise direction to result in the position shown in FIGURE 3. As soon as flange 103 clears notch 134, contacts 34, 36 will become separated thus severing circuit 40 and precluding the further passage of electrical current to plug 20.

The only operation required to reset latch arm 102 from the position shown in FIGURE 3 is to remove plug 20 which releases the binding engagement between block 128, cam 118 and flange 113 to allow return spring 114 to pivot load carrying arm 88 and positioner 104 in a clockwise direction. To avoid any possibility of flange 103 of latch arm 102 becoming fouled on armature plate 138, an arcuate camming surface 162 is formed thereon to allow the smooth movement of flange 103 across plate 136. The only operation required to reactivate circuit 40 is the replacement of male prongs 26 in openings 30, 31, resulting in the closed circuit arrangement of FIGURE 2. It should be apparent that solenoid 152 should be selected to trip armature 136 at a desired current flow through circuit 40. By balancing the strength of the solenoid coil against the weight of plunger 156 it will be apparent that a normal current flow through circuit 40 will not activate solenoid 152 while a current surge will retract plunger 156.

It will be readily apparent that solenoid 152 will sever circuit 40 only when a relatively high current rate is achieved within power delivery circuit 40 thus allowing a prolonged current flow above a desired level. To obviate such a disadvantage, bimetallic strip 148 is constructed such that a normal current flow will produce a given amount of temperature increase thus flexing strip 148 in a downward direction a predetermined amount. The increase in current flow through circuit 40 will result in an increase in temperature of strip 148 thus creating additional downward flexing whereby the free end of strip 148 may contact the free end of armature 136 thus freeing flange 103 from within notch 134. When such a condition occurs, helical spring 114 will rotate load carrying arm 88 in a counter-clockwise direction separating contacts 34, 36 ceasing current flow through circuit 40.

ALTERNATIVE EMBODIMENT Referring now to FIGURES 5 to 7 inclusive, a modified form of the electrical receptacle of the instant invention is designated generally at in the description of which identical reference characters will be used for identical elements or combinations of elements for purposes of clarity and brevity with new or different element sbeing provided with new reference characters. The main difference between receptacles 10 and 170 resides in the provision of a blocking means designated generally at 172 requiring the insertion of a dual pronged device to deliver electrical potential to a pair of outlet terminals shown generally at 420, 440, which correspond to outlet terminals 42, 44 of receptacle 10. The remaining differences reside in the rearrangement of the components of receptacle 10 for the operation of blocking means 172.

A connecting block 174 is rotatably mounted by a pivot pin 176 on a support block 178 located between slots 14 in much the same manner that connecting block 128 is supported on block 132. In common with the operation of receptacle 10, the forced rotation of connecting block 174 in a counter-clockwise direction act-s to manipulate load carrying arm 88 closing contacts 34, 36 which are hidden behind a second support block 180. Connecting block 174 carries a blocking protuberance 182 spaced from pivot pin 176 in the path of a blocking lever 184 pivotally mounted on support block 180 by a pivot pin 186 and biased in a clockwise direction by a coiled spring wire 188. Support block 178 is provided with a forwardly extending ledge 190 limiting the clockwise rotation of clocking lever 184 such that the forward end thereof will be engaged with blocking protuberance 182 when connecting block 174 is rotated in a clockwise direction by a single probe 192 as may be seen in FIGURE 6.

It will be seen, therefore, that the insertion of a single probe 192 into rightmost slot 14 will not manipulate load carrying arm 88 since connecting block 174 is effectively precluded from contact with cam 118. The insertion of a dual probe device, such as electric plug 20 as may be seen in FIGURE 7, will allow connecting block 174 to contact cam 118 in order to manipulate load carrying arm 88, close contacts 34, 36 and deliver electrical potential across outlet terminals 420, 440 in much the same manner that receptacle operates. This is achieved since leftmost prong 26 of plug rotates blocking lever 1 84 out of the path of rotation of blocking protuberance 182 before rightmost prong 26 contacts connecting block 174. It is thus seen that the insertion of a single probe through rightmost slot 14 will not deliver electrical potential across terminals 420, 440 since power delivery circuit is open because of the spaced apart relation of contacts 34, 36. As will be more fully pointed out hereinafter, it will be apparent that the insertion of a single probe into the leftmost slot 14 will not injure an individual so doing since power delivery circuit 40 cannot be closed unless connecting block 174 is forcibly rotated in a counterclockwise direction.

Outlet terminal 420 is made of a spring metal member and is provided with a bulge 194 adjacent the arcuate end of connecting block 174 and a curved end 196 which contacts rightmost prong 26 in much the same manner that arcuate camming surface 74 of outlet terminal 14 contacts leftmost prong 26. The upper end of outlet terminal 420 includes a U-shaped connector 198 surrounding the upper end of a block 200 and is secured thereto by a threaded screw 202 which acts as a releasable connegtor between solenoid conduit 154 and outlet terminal 42 Outlet terminal 440 includes a U-shaped spring metal end having a long leg 204 extending adjacent leftmost slot 14 and is equipped with an arcuate camming edge 206 which, when depressed by a leftmost prong 26, resides in an indentation 208 formed by support block 180. Outlet terminal 440 also includes a horizontal section 210 secured to support block 180 by a threaded screw 212 which acts to provide a releasable connection between electrical wire leading to an alternating current power source as previously mentioned. Camming edge 206 of outlet terminal 440 is normally positioned in the path of leftmost prong 26 such that the insertion of electrical plug 20 cams long leg 204 to the left as shown in FIGURE 5 insuring electrical contact therebetween. It will be apparent that the insertion of probe 192 into leftmost slot 14 will not deliver electrical potential across terminals 420, 440 since contacts 34, 36 cannot be closed except by connecting block 174.

SUMMARY OF OPERATION ergization of circuit 40 upon a prolonged rate of current flow slightly above a predetermined value and the resetting of current opening means 46 upon the retraction of plug 20.

The de-energization of circuit 40 when plug 20 is removed is the result of the action of return spring 114 on a positioner 104 and consequently on load carrying arm 88 to shift load carrying arm 88 to the right as may be seen in FIGURE 4. The energization of circuit 40 upon the insertion of plug 20 into openings 30, 31 is caused by the shifting of load carrying arm to the left to juxtapose contacts 34, 36. The de-energization of circuit 40 because of an impulse overload is the result of a high rate of current flow through solenoid 152 retracting plunger 156 disengaging notch 134 from flange 103 of latch arm 102. The de-energization of circuit 40 when a prolonged current flow slightly greater than a predetermined value is caused by bimetallic strip 148 flexing because of the increased temperature thereof contacting armature plate 136 and releasing flange 103 from notch 134. In the event that bimetallic strip 148 does not flex sufficiently to contact the free end of plate 136, a protuberance 137 may be formed on the end thereof.

It is now seen that there is herein provided an improved electrical receptacle having all of the objects and advantages of the instant invention and others, including many advantages of great practical utility and commercial importance.

Since many embodiments may be made of the instant inventive concept, and since many modifications may be made of the embodiments hereinbefore shown and described, it is to be understood that the foregoing is to be interpreted merely as illustrative and not in a limiting sense.

I claim:

1. In an electrical receptacle of the type having an apertured face plate, terminals adjacent said apertures engageable with the prongs of a removable electrical plug, movable contacts in a receptacle circuit for normally deenergizing the terminals when the plug is removed, and motion transmitting means translating the inward movement of the plug into closing movement of.

the contacts, the motion transmitting means being biased toward the deenergized position and engageable with the prongs for holding the contacts in closed position, the improvement comprising current responsive means for moving at least a pair of the contacts apart upon the flow of current through the circuit in excess of a predetermined amount, and

means held in inoperative relation upon opening of said contact, by said current responsive means through the motion transmitting means by the plug in the receptacle for returning the motion transmitting means and the contacts to the normally deenergized position upon removal of the plug.

2. An electrical receptacle comprising:

means forming outlet terminals for engagement with a removable electric plug,

a power delivery circuit connected to said outlet terminals for delivering electrical potential to said outer terminals only when said plug is engaged therewith including a pair of normally open electrical contacts,

means mounting said contacts for relative movement from a closed position for delivering electrical potential to said terminals to an open position to prevent delivery of electrical potential to said terminals when said plug is not in engagement therewith,

motion transmitting means engageable with the prongs of said removable plug when said plug is adjacent said terminals for closing said contacts upon the retraction and reinsertion of said plug in said terminals, and

means in said circuit for opening said contacts when said circuit carries a current flow above a predetermined value and said plug is in engagement with said terminals.

3. The structure of claim 2 wherein said circuit opening means includes overload means for opening said circuit P Prolonged iv ry of a current through said circuit at rates slightly above said predetermined value, and

impulse overload means for opening said circuit upon a current pulse substantially greater than said prewherein said motion transmitting means includes a block pivotally mounted adjacent at least one of said openings for engagement with and rotation by a male prong inserted into said openings, at positioner determined value and substantially greater than pivotally mounted on said receptacle, means transsaid current flow necessary to actuate the first mitting the rotational movement of said block to said named overload means. positioner, spring means connecting said positioner 4. An electric receptacle comprising: and said load arm biasing said load arm away from a face plate forming prong receiving slots, said positioner in a first direction, spring means biasmeans on said face plate forming outlet terminals ading said positioner toward said load arm in a second I jacent said slots engageable with a removable elecdirection, said mounting means including means slidtric plug, ably-and pivotally mounting said load arm on said a power delivery circuit carried by said face plate conpositioner for engaging said load arm with said latch nected to said outlet terminals for delivering elecmeans of said circuit opening means and for clostrical potential to said outlet terminals including a ing said contacts upon rotation of said block.

pair of electrical contacts,

6. The structure of claim 5 wherein said latch means includes an armature mounted for movement from a first position holding said load arm in said contact closing position to a second position releasing said load arm means mounting said contacts for relative movement from a closed position for delivering electrical potential to said terminal to an open position to cease delivery of electrical potential to said terminals, motion transmitting means engageable with the prongs of said removable plug when said plug is adjacent said terminals for moving said mounting means to said closed contact position upon retraction and reinsertion of said plug in said terminals, and circuit opening means in said circuit for moving said mounting means from said closed contact position to said open contact position when said circuit carries a current flow above a predetermined value,

from said closing position, said armature moving means including a solenoid in said power delivery circuit.

7. The structure of claim 5 wherein said latch means includes an armature mounted for movement from a first position holding said load arm in said contact closing position, said armature moving means including a bi metallic strip in said power delivery circuit.

8. An electric receptacle comprising: a face plate forming prong receiving openings, means on said face plate forming outlet terminals adjasaid circuit opening means and said mounting means c nt said openings for engagement with a removable including latching means for selectively holding said electric plug, I mounting means in said contact closing position, a power delivery circuit connected to said outlet terfurther including means for unlocking said latching minals for delivering electrical potential to said outrneans for releasing said mounting means from said let terminals including a pair of electrical contacts, contact closing position, means mounting said contacts for relative movement wherein said unlocking means includes overload means from a closed position for delivering electrical potenfor unlocking said latching means when said circuit tial to Said terminals to all p Position to cease carries a prolonged current flow at a rate slightly delivery of electrical potential to said terminals, said above said predetermined value, and mounting means including a load arm carrying one wherein said unlocking means includes impulse 'over- 40 of said contacts and mounted for movement on said load means in series with said overload means for receptacle, and means biasing said load arm toward unlocking said latching means when said circuit can said contact opening position, ries a current impulse substantially greater than said m i n transmitting means engageable with the prongs predetermined value and substantially greater than f id removab plug When Said plug is adjac nt said current fiow necessary to actuate the first named said terminals for moving said load arm to said overload means. closed contact position upon movement of said 5. An electric receptacle comprising: motion transmitting means by the insertion of said a face plate forming prong receiving openings, removable plug, means on the face plate forming outlet terminals admeans in Said circuit p Said contacts when jacent said openings for engagement ith a removsaid circuit carries a current flow above a predeterable electric plug, mined value including latch means holding said load a power delivery circuit connected to said outlet termiarm in Said Coma Closing Position, and means for nals for delivering electrical potential to said outlet unlocking Said latch means When Said Current @Xceeds terminals including a pair of electrical contacts, Said predetermined Value,

means mounting said contacts for relative movement wherein said latch means includes an armature mounted from a closed position for delivering electrical pofor movement from a first Position holding Said load tential to said terminals to an open position to cease arm in Said Contact Closing POSifiOIl to a Second 1 delivery of electrical potential to said terminals, tion releasing Said load arm from Said Contact 6108' said mounting means including a load arm carrying ing Position, and one of said contacts and being mounted for moveincluding means for moving said armature from said ment on said receptacle, and means normally biasfirst Position to Said Second Positioning said load arm toward said contact opening 110- An electric receptacle comprising! sition, a face plate forming prong receiving openings, motion transmitting means engageable with the prongs means 011 Said face Plate forming Outlet terminals i of said removable plug when said plug is adjacent 5 Cent Said Openings for engagement with a removable said terminals for moving said load arm to said electric Plug, closed contact position upon movement of said a power delivery circuit connected to said outlet tertion transmitting means by th insertion of id minals for delivering electrical potential to said outbl l d let terminals including a pair of electrical contacts, means in said circuit for opening said contacts when means mounting Said Contacts relative movement aid circuit carries a current flow abo a predefrom a closed position for delivering electrical potentermined value including latch means holding said l to Said terminals to an open position to cease load arm in said contact closing position, and means delivery of electrical potential to said terminals, said for unlocking said latch means when said current exmounting means including a load arm carrying one ceeds said predetermined value, of said contacts and mounted for movement on said receptacle, and means biasing said load arm toward said contact Opening position,

motion transmitting means engageable with the prongs of said removable plug when said plug is adjacent said terminals for moving said load arm to said closed contact position upon movement of said motion transmitting means by the insertion of said removable plug,

means in said circuit for opening said contacts when said circuit carries a current flow above a predetermined value including latch means holding said load arm in said contact closing position, and means for unlocking said latch means when said current exceeds said predetermined value,

including means precluding the actuation of said motion transmitting means unless at least two of said openings receive a prong, said actuation precluding means including blocking means for engagement with a prong inserted therein and means mounting said blocking means for movement between a first position overlying said one opening in position to preclude movement of said motion transmitting means to a second position out of the path of movement of said motion transmitting means upon insertion and retraction of a prong into said one opening.

10. In an electrical receptacle of the type constructed to receive a removable electrical plug and including a pair of contacts and a current sensing device which is actuated by current in excess of a predetermined current flow, the improvement comprising:

means for normally positioning said contacts in a first open condition;

means operably interconnecting the sensing device and the contacts for moving the contacts from a closed position to a second open position upon actuation of said sensing device, and

means operably interconnecting the contacts and being engageable by said plug for returning said contacts to said first open condition from said second open position upon removal of said plug from said receptacle and closing the contacts upon re-insertion of said plug.

11. The receptacle of claim wherein the closing means comprises:

means engageable with said plug for closing said contacts only when said plug is received in said receptacle.

12. The receptacle of claim 11 wherein said closing means is engaged by one prong of said plug and further comprising:

means engageable by a second prong of said plug of blocking operation of said closing means except when said second prong engages said blocking means.

13. The receptacle of claim 11 further comprising:

a second current sensing device in the receptacle disposed and constructed for triggering the means operably interconnecting the first sensing device and the contacts,

one of said current sensing devices being sensitive to a small long-term current excess and the other of said current sensing devices being sensitive to a large short-term current excess.

14. The receptacle of claim 10 further comprising:

a second current sensing device in the receptacle disposed and constructed for triggering the means operably interconnecting the first sensing device and the contacts,

one of said current sensing devices being sensitive to a small long-term current excess and the other of said current sensing devices being sensitive to a large short-term current excess.

15. An electrical receptacle comprising:

outlet terminals for engagement with a removable plug,

a pair of electrical contacts,

contact mounting means carrying one of said contacts,

said mounting means being mounted in said receptacle for moving said contact from a normally open position to a closed position and to an abnormally open position,

current sensing latch means normally engaging said contact mounting means for normally preventing said contact from being moved to said abnormally open position and for releasing said contact mounting means for moving said contact to said abnormally open position upon the flow of current in excess of a predetermined value,

motion transmitting means operable by engagement of said plug in said receptacle for moving said mounting means to close said contacts, and

means operable by removal of said plug from engagement in said receptacle for returning said mounting means for moving said contact to said normally open position from said closed position and from said abnormally open position.

References Cited UNITED STATES PATENTS 783,995 2/ 1905 Cook 200-1l5 2,826,652 3/1958 Piplack 2005l.09

2,934,623 4/1960 Christensen ZOO-115.5

3,169,239 2/1965 Lacey 2.00--1l3 BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITIER, Assistant Examiner. 

2. AN ELECTRICAL RECEPTACLE COMPRISING: MEANS FORMING OUTLET TERMINALS FOR ENGAGEMENT WITH A REMOVABLE ELECTRIC PLUG, A POWER DELIVERY CIRCUIT CONNECTED TO SAID OUTLET TERMINALS FOR DELIVERING ELECTRICAL POTENTIAL TO SAID OUTER TERMINALS ONLY WHEN SAID PLUG IS ENGAGED THEREWITH INCLUDING A PAIR OF NORMALLY OPEN ELECTRICAL CONTACTS, MEANS MOUNTING SAID CONTACTS FOR RELATIVE MOVEMENT FROM A CLOSED POSITION FOR DELIVERING ELECTRICAL POTENTIAL TO SAID TERMINALS TO AN OPEN POSITION TO PREVENT DELIVERY OF ELECTRICAL POTENTIAL TO SAID TERMINALS WHEN SAID PLUG IS NOT IN ENGAGEMENT THEREWITH, MOTION TRANSMITTING MEANS ENGAGEABLE WITH THE PRONGS OF SAID REMOVABLE PLUG WHEN SAID PLUG IS ADJACENT SAID TERMINALS FOR CLOSING SAID CONTACTS UPON THE RETRACTION AND REINSERTION OF SAID PLUG IN SAID TERMINALS, AND MEANS IN SAID CIRCUIT FOR OPENING SAID CONTACTS WHEN SAID CIRCUIT CARRIES A CURRENT FLOW ABOVE A PREDETERMINED TERMINAL VALUE AND SAID PLUG IS IN ENGAGEMENT WITH SAID TERMINALS. 